The present invention relates to an observation position and forming position determining method in an observation/forming apparatus using a charged particle apparatus such as a focused ion beam apparatus FIB (Focused Ion Beam) scanning electron microscope (SEM), and to an apparatus therefor.
The conventional FIB/SEM observation position alignment utilizing an optical microscope image includes two methods. The first is a method of comparing two images to align them on a coordinate and performing marking with an FIB to enable location of a mark position by use of an optical microscope, thereby confirming the position. The second is a method for aligning positions of an optical microscope image and an FIB and SEM image from a coordinate relationship. For example, such a method is disclosed in JP-A-9-097585.
There is a problem in that the above described technology in damage is caused to a sample due to FIB/SEM and labor and time is required in forming position specifying time and also in detailed position specifying accuracy to conduct section observation.
For example, in a semiconductor manufacturing process, highly integrated semiconductor manufacture has recently been obtained in multi-layer structures using planar layers as interconnect line width has been reduced. On the semiconductor surface a transparent passivation film is formed. Due to this, because the passivation film does not transmit electrons or ions, it has become impossible to observe a target position inside the planarized film after planarization. Accordingly, optical observation images are required to supplement positioning observation/forming position location for FIB/SEM use. However, the section forming of an interconnect of 1 micron or smaller requires observation/forming position alignment of 1 micron or less. However, there is a problem in that using only stage coordinate movement positioning an accuracy of 1 micron or smaller is difficult to easily achieve.
Also, there is a problem of occurrence of reference (contamination) on a sample encountered in long time or strong electron/ion beam observation.
It is an object of the present invention to provide an apparatus which is capable of improving observation/forming position positional accuracy using FIB/SEM and reducing sample damage by an electron/ion beam due to observation time shortening.